Abstract: To research the relationship between passive smoking and blood lead level,the sitution of passive smoking were investigate in 395 preschool children aged 2～6 years with self-designed Questionnaire and their blood lead level were measured to analyze the the relationship between passive smoking and blood lead level.The results showed that the blood lead level and the prevalence rate of lead poisoning(26.98μg/dl,87.45%)in the observation group were higher than that in the contral group(22.24μg/dl,60.81%) significiantly,as the passive smoking increasing,they increased gradually(P<0.05),the Bpb was the highest in 2 year old observation group than in the others,multiple regression analysis showed that passive smoking were associated with blood lead levels.It were obvious that passive smoking affected the blood lead levels of preschool children,2 year old was probably the critical period of passive smoking exposure.